/*
 * Created on 31-Jul-2004
 * Created by Paul Gardner
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package org.gudy.azureus2.core3.disk.impl.access.impl;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import org.gudy.azureus2.core3.disk.DiskManagerException;
import org.gudy.azureus2.core3.disk.DiskManagerFileInfo;
import org.gudy.azureus2.core3.disk.DiskManagerPiece;
import org.gudy.azureus2.core3.disk.DiskManagerWriteRequest;
import org.gudy.azureus2.core3.disk.DiskManagerWriteRequestListener;
import org.gudy.azureus2.core3.disk.impl.DiskManagerFileInfoImpl;
import org.gudy.azureus2.core3.disk.impl.DiskManagerHelper;
import org.gudy.azureus2.core3.disk.impl.access.DMWriter;
import org.gudy.azureus2.core3.disk.impl.piecemapper.DMPieceList;
import org.gudy.azureus2.core3.disk.impl.piecemapper.DMPieceMapEntry;
import org.gudy.azureus2.core3.logging.LogEvent;
import org.gudy.azureus2.core3.logging.LogIDs;
import org.gudy.azureus2.core3.logging.Logger;
import org.gudy.azureus2.core3.util.AEMonitor;
import org.gudy.azureus2.core3.util.AESemaphore;
import org.gudy.azureus2.core3.util.Debug;
import org.gudy.azureus2.core3.util.DirectByteBuffer;
import org.gudy.azureus2.core3.util.DirectByteBufferPool;
import org.gudy.azureus2.core3.util.SystemTime;

import com.aelitis.azureus.core.diskmanager.access.DiskAccessController;
import com.aelitis.azureus.core.diskmanager.access.DiskAccessRequest;
import com.aelitis.azureus.core.diskmanager.access.DiskAccessRequestListener;
import com.aelitis.azureus.core.diskmanager.cache.CacheFile;
import com.aelitis.azureus.core.diskmanager.cache.CacheFileManagerException;

/**
 * @author parg
 * 
 */

public class DMWriterImpl implements DMWriter {
    private static final LogIDs LOGID = LogIDs.DISK;

    private static final int MIN_ZERO_BLOCK = 1 * 1024 * 1024; // must be mult of 1024 (see init below)

    private DiskManagerHelper disk_manager;
    private DiskAccessController disk_access;

    private int async_writes;
    private Set write_requests = new HashSet();
    private AESemaphore async_write_sem = new AESemaphore("DMWriter::asyncWrite");

    private boolean started;

    private volatile boolean stopped;

    private int pieceLength;
    private long totalLength;

    private boolean complete_recheck_in_progress;

    private AEMonitor this_mon = new AEMonitor("DMWriter");

    public DMWriterImpl(DiskManagerHelper _disk_manager) {
        disk_manager = _disk_manager;
        disk_access = disk_manager.getDiskAccessController();

        pieceLength = disk_manager.getPieceLength();
        totalLength = disk_manager.getTotalLength();
    }

    public void start() {
        try {
            this_mon.enter();

            if (started) {

                throw (new RuntimeException("DMWWriter: start while started"));
            }

            if (stopped) {

                throw (new RuntimeException("DMWWriter: start after stopped"));
            }

            started = true;

        } finally {

            this_mon.exit();
        }
    }

    public void stop() {
        int write_wait;

        try {
            this_mon.enter();

            if (stopped || !started) {

                return;
            }

            stopped = true;

            write_wait = async_writes;

        } finally {

            this_mon.exit();
        }

        // wait for writes

        long log_time = SystemTime.getCurrentTime();

        for (int i = 0; i < write_wait; i++) {

            long now = SystemTime.getCurrentTime();

            if (now < log_time) {

                log_time = now;

            } else {

                if (now - log_time > 1000) {

                    log_time = now;

                    if (Logger.isEnabled()) {

                        Logger.log(new LogEvent(disk_manager, LOGID, "Waiting for writes to complete - " + (write_wait - i) + " remaining"));
                    }
                }
            }

            async_write_sem.reserve();
        }
    }

    public boolean isChecking() {
        return (complete_recheck_in_progress);
    }

    public boolean zeroFile(DiskManagerFileInfoImpl file, long length) throws DiskManagerException {
        CacheFile cache_file = file.getCacheFile();

        try {
            if (length == 0) { // create a zero-length file if it is listed in the torrent

                cache_file.setLength(0);

            } else {
                int buffer_size = pieceLength < MIN_ZERO_BLOCK ? MIN_ZERO_BLOCK : pieceLength;

                buffer_size = ((buffer_size + 1023) / 1024) * 1024;

                DirectByteBuffer buffer = DirectByteBufferPool.getBuffer(DirectByteBuffer.AL_DM_ZERO, buffer_size);

                long remainder = length;
                long written = 0;

                try {
                    final byte[] blanks = new byte[1024];

                    for (int i = 0; i < buffer_size / 1024; i++) {

                        buffer.put(DirectByteBuffer.SS_DW, blanks);
                    }

                    buffer.position(DirectByteBuffer.SS_DW, 0);

                    while (remainder > 0 && !stopped) {

                        int write_size = buffer_size;

                        if (remainder < write_size) {

                            write_size = (int) remainder;

                            buffer.limit(DirectByteBuffer.SS_DW, write_size);
                        }

                        final AESemaphore sem = new AESemaphore("DMW&C:zeroFile");
                        final Throwable[] op_failed = { null };

                        disk_access.queueWriteRequest(cache_file, written, buffer, false, new DiskAccessRequestListener() {
                            public void requestComplete(DiskAccessRequest request) {
                                sem.release();
                            }

                            public void requestCancelled(DiskAccessRequest request) {
                                op_failed[0] = new Throwable("Request cancelled");

                                sem.release();
                            }

                            public void requestFailed(DiskAccessRequest request, Throwable cause) {
                                op_failed[0] = cause;

                                sem.release();
                            }

                            public int getPriority() {
                                return (-1);
                            }

                            public void requestExecuted(long bytes) {
                            }
                        });

                        sem.reserve();

                        if (op_failed[0] != null) {

                            throw (op_failed[0]);
                        }

                        buffer.position(DirectByteBuffer.SS_DW, 0);

                        written += write_size;
                        remainder -= write_size;

                        disk_manager.setAllocated(disk_manager.getAllocated() + write_size);

                        disk_manager.setPercentDone((int) ((disk_manager.getAllocated() * 1000) / totalLength));
                    }
                } finally {

                    buffer.returnToPool();
                }

                cache_file.flushCache();
            }

            if (stopped) {

                return false;
            }
        } catch (Throwable e) {

            Debug.printStackTrace(e);

            throw new DiskManagerException(e);
        }

        return true;
    }

    public DiskManagerWriteRequest createWriteRequest(int pieceNumber, int offset, DirectByteBuffer buffer, Object user_data) {
        return (new DiskManagerWriteRequestImpl(pieceNumber, offset, buffer, user_data));
    }

    public boolean hasOutstandingWriteRequestForPiece(int piece_number) {
        try {
            this_mon.enter();

            Iterator it = write_requests.iterator();

            while (it.hasNext()) {

                DiskManagerWriteRequest request = (DiskManagerWriteRequest) it.next();

                if (request.getPieceNumber() == piece_number) {

                    return (true);
                }
            }

            return (false);

        } finally {

            this_mon.exit();
        }
    }

    public void writeBlock(final DiskManagerWriteRequest request, final DiskManagerWriteRequestListener _listener)

    {
        request.requestStarts();

        final DiskManagerWriteRequestListener listener = new DiskManagerWriteRequestListener() {
            public void writeCompleted(DiskManagerWriteRequest request) {
                request.requestEnds(true);

                _listener.writeCompleted(request);
            }

            public void writeFailed(DiskManagerWriteRequest request, Throwable cause) {
                request.requestEnds(false);

                _listener.writeFailed(request, cause);
            }
        };

        try {
            int pieceNumber = request.getPieceNumber();
            DirectByteBuffer buffer = request.getBuffer();
            int offset = request.getOffset();

            // Do not allow to write in a piece marked as done. we can get here if

            final DiskManagerPiece dmPiece = disk_manager.getPieces()[pieceNumber];

            if (dmPiece.isDone()) {

                // Debug.out( "write: piece already done (" + request.getPieceNumber() + "/" + request.getOffset());

                buffer.returnToPool();

                listener.writeCompleted(request); // XXX: no writing was done; is this neccesary for complete()?

            } else {

                int buffer_position = buffer.position(DirectByteBuffer.SS_DW);
                int buffer_limit = buffer.limit(DirectByteBuffer.SS_DW);

                // final long write_length = buffer_limit - buffer_position;

                int previousFilesLength = 0;

                int currentFile = 0;

                DMPieceList pieceList = disk_manager.getPieceList(pieceNumber);

                DMPieceMapEntry current_piece = pieceList.get(currentFile);

                long fileOffset = current_piece.getOffset();

                while ((previousFilesLength + current_piece.getLength()) < offset) {

                    previousFilesLength += current_piece.getLength();

                    currentFile++;

                    fileOffset = 0;

                    current_piece = pieceList.get(currentFile);
                }

                List chunks = new ArrayList();

                // Now current_piece points to the first file that contains data for this block

                while (buffer_position < buffer_limit) {

                    current_piece = pieceList.get(currentFile);

                    long file_limit =
                            buffer_position + ((current_piece.getFile().getLength() - current_piece.getOffset()) - (offset - previousFilesLength));

                    if (file_limit > buffer_limit) {

                        file_limit = buffer_limit;
                    }

                    // could be a zero-length file

                    if (file_limit > buffer_position) {

                        long file_pos = fileOffset + (offset - previousFilesLength);

                        chunks.add(new Object[] { current_piece.getFile(), new Long(file_pos), new Integer((int) file_limit) });

                        buffer_position = (int) file_limit;
                    }

                    currentFile++;

                    fileOffset = 0;

                    previousFilesLength = offset;
                }

                DiskManagerWriteRequestListener l = new DiskManagerWriteRequestListener() {
                    public void writeCompleted(DiskManagerWriteRequest request) {
                        complete();

                        listener.writeCompleted(request);
                    }

                    public void writeFailed(DiskManagerWriteRequest request, Throwable cause) {
                        complete();

                        if (dmPiece.isDone()) {

                            // There's a small chance of us ending up writing the same block twice around
                            // the time that a file completes and gets toggled to read-only which then
                            // fails with a non-writeable-channel exception

                            // Debug.out( "writeFailed: piece already done (" + request.getPieceNumber() + "/" + request.getOffset() + "/" +
                            // write_length );

                            if (Logger.isEnabled()) {

                                Logger.log(new LogEvent(disk_manager, LOGID, "Piece " + dmPiece.getPieceNumber()
                                        + " write failed but already marked as done"));
                            }

                            listener.writeCompleted(request);

                        } else {

                            disk_manager.setFailed("Disk write error - " + Debug.getNestedExceptionMessage(cause));

                            Debug.printStackTrace(cause);

                            listener.writeFailed(request, cause);
                        }
                    }

                    protected void complete() {
                        try {
                            this_mon.enter();

                            async_writes--;

                            if (!write_requests.remove(request)) {

                                Debug.out("request not found");
                            }

                            if (stopped) {

                                async_write_sem.release();
                            }
                        } finally {

                            this_mon.exit();
                        }
                    }
                };

                try {
                    this_mon.enter();

                    if (stopped) {

                        buffer.returnToPool();

                        listener.writeFailed(request, new Exception("Disk writer has been stopped"));

                        return;

                    } else {

                        async_writes++;

                        write_requests.add(request);
                    }

                } finally {

                    this_mon.exit();
                }

                new requestDispatcher(request, l, buffer, chunks);
            }
        } catch (Throwable e) {

            request.getBuffer().returnToPool();

            disk_manager.setFailed("Disk write error - " + Debug.getNestedExceptionMessage(e));

            Debug.printStackTrace(e);

            listener.writeFailed(request, e);
        }
    }

    protected class requestDispatcher implements DiskAccessRequestListener {
        private DiskManagerWriteRequest request;
        private DiskManagerWriteRequestListener listener;
        private DirectByteBuffer buffer;
        private List chunks;

        private int chunk_index;

        protected requestDispatcher(DiskManagerWriteRequest _request, DiskManagerWriteRequestListener _listener, DirectByteBuffer _buffer,
                List _chunks) {
            request = _request;
            listener = _listener;
            buffer = _buffer;
            chunks = _chunks;

            /*
             * String str = "Write: " + request.getPieceNumber() + "/" + request.getOffset() + ":"; for (int i=0;i<chunks.size();i++){ Object[] entry
             * = (Object[])chunks.get(i); String str2 = entry[0] + "/" + entry[1] +"/" + entry[2]; str += (i==0?"":",") + str2; } System.out.println(
             * str );
             */

            dispatch();
        }

        protected void dispatch() {
            try {
                if (chunk_index == chunks.size()) {

                    listener.writeCompleted(request);

                } else {

                    if (chunk_index == 1 && chunks.size() > 32) {

                        // for large numbers of chunks drop the recursion approach and
                        // do it linearly (but on the async thread)

                        for (int i = 1; i < chunks.size(); i++) {

                            final AESemaphore sem = new AESemaphore("DMW&C:dispatch:asyncReq");
                            final Throwable[] error = { null };

                            doRequest(new DiskAccessRequestListener() {
                                public void requestComplete(DiskAccessRequest request) {
                                    sem.release();
                                }

                                public void requestCancelled(DiskAccessRequest request) {
                                    Debug.out("shouldn't get here");
                                }

                                public void requestFailed(DiskAccessRequest request, Throwable cause) {
                                    error[0] = cause;

                                    sem.release();
                                }

                                public int getPriority() {
                                    return (-1);
                                }

                                public void requestExecuted(long bytes) {
                                }
                            });

                            sem.reserve();

                            if (error[0] != null) {

                                throw (error[0]);
                            }
                        }

                        listener.writeCompleted(request);

                    } else {

                        doRequest(this);
                    }
                }
            } catch (Throwable e) {

                failed(e);
            }
        }

        protected void doRequest(final DiskAccessRequestListener l)

        throws CacheFileManagerException {
            Object[] stuff = (Object[]) chunks.get(chunk_index++);

            final DiskManagerFileInfoImpl file = (DiskManagerFileInfoImpl) stuff[0];

            buffer.limit(DirectByteBuffer.SS_DR, ((Integer) stuff[2]).intValue());

            if (file.getAccessMode() == DiskManagerFileInfo.READ) {

                if (Logger.isEnabled())
                    Logger.log(new LogEvent(disk_manager, LOGID, "Changing " + file.getFile(true).getName() + " to read/write"));

                file.setAccessMode(DiskManagerFileInfo.WRITE);
            }

            boolean handover_buffer = chunk_index == chunks.size();

            DiskAccessRequestListener delegate_listener = new DiskAccessRequestListener() {
                public void requestComplete(DiskAccessRequest request) {
                    l.requestComplete(request);

                    file.dataWritten(request.getOffset(), request.getSize());
                }

                public void requestCancelled(DiskAccessRequest request) {
                    l.requestCancelled(request);
                }

                public void requestFailed(DiskAccessRequest request, Throwable cause) {
                    l.requestFailed(request, cause);
                }

                public int getPriority() {
                    return (-1);
                }

                public void requestExecuted(long bytes) {
                }
            };

            disk_access.queueWriteRequest(file.getCacheFile(), ((Long) stuff[1]).longValue(), buffer, handover_buffer, delegate_listener);
        }

        public void requestComplete(DiskAccessRequest request) {
            dispatch();
        }

        public void requestCancelled(DiskAccessRequest request) {
            // we never cancel so nothing to do here

            Debug.out("shouldn't get here");
        }

        public void requestFailed(DiskAccessRequest request, Throwable cause) {
            failed(cause);
        }

        public int getPriority() {
            return (-1);
        }

        public void requestExecuted(long bytes) {
        }

        protected void failed(Throwable cause) {
            buffer.returnToPool();

            listener.writeFailed(request, cause);
        }
    }
}
